Eiteneer, B., Yu, C.-L., Goldenberg, M., and Frenklach, M. (1998)
Determination of Rate Coefficients for Reactions of Formaldehyde Pyrolysis
and Oxidation in the Gas Phase
J. Phys. Chem. A 1998, 102, 5196.
Abstract
Seven mixtures of formaldehyde and oxygen diluted in argon were studied behind
reflected shock waves at temperatures from 1340 to 2270 K and pressures from 0.7
to 2.5 atm. Mixture compositions covered a range from pure pyrolysis to lean
oxidation at a stoichiometric ratio of 0.17. The progress of reaction was
monitored by laser absorption of CO molecules. Experimental rates of CO
formation were found to be 80% higher, in the case of pyrolysis, and 30% lower,
under lean oxidation, than those predicted by the current reaction model,
GRI-Mech 1.2. The collected experimental data were subjected to extensive
detailed chemical kinetics analysis, including optimization with the solution
mapping technique. The analysis identified a strong correlation between two
rate constants. Assuming a recent literature expression (Irdam et al. (1993)) for one of them (58) produced k54 =
2.66E+24 T^(-2.57) exp(-215/T) cm6 mol-2 s-1
for the reaction (54) H + HCO + M
-> CH2O + M. A new expression was developed for the reaction (121) HO2 +
CH2O -> HCO + H2O2, k121 = 4.11E+4
T^2.5 exp(-5136/T) cm3 mol-1 s-1, by fitting
the present and literature results. With these modifications, the new reaction
model provides good agreement with our experimental data and an acceptable
agreement with most literature experimental observations.
REACTION RATE COEFFICIENTS SUGGESTED IN THIS WORK:
GRI-Mech
Number
('-' sign
means
reverse) |
Reaction |
Rate Coefficient
A T^n exp(-E/RT) |
Temperature
Range
(K) |
A
(mol,cm3,s) |
n
(T in K) |
E
(cal/mol) |
| 54 |
H + HCO + M -> CH2O + M |
2.66E+24 |
-2.57 |
425 |
1340-2270 |
| 121 |
HO2 + CH2O -> HCO + H2O2 |
4.11E+4 |
2.5 |
10205 |
541-1600 |